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<p class='vspace'></p><h2>% (modulo)</h2>
<h4>Description</h4>
<p>Returns the remainder from an integer division
</p><h4>Syntax</h4>
<p>result = value1 % value2
</p>
<p class='vspace'></p><h4>Parameters</h4>
<p>value1: a byte, char, int, or long
</p>
<p class='vspace'></p><p>value2: a byte, char, int, or long
</p>
<p class='vspace'></p><h4>Returns</h4>
<p>The remainder from an integer division.
</p>
<p class='vspace'></p><h4>Examples</h4>
<pre>x = 7 % 5;   // x now contains 2
x = 9 % 5;   // x now contains 4
x = 5 % 5;   // x now contains 0
x = 4 % 5;   // x now contains 4

</pre>
<p class='vspace'></p><p>The modulo operator is useful for tasks such as making an event occur at regular periods or making a memory array roll over
</p>
<p class='vspace'></p><h4>Example Code</h4>
<pre>
// check a sensor every 10 times through a loop
void loop(){
i++;
if ((i % 10) == 0){          // read sensor every ten times through loop
   x = analogRead(sensPin);   
   }
/ ...
}

// setup a buffer that averages the last five samples of a sensor

int senVal[5];  // create an array for sensor data
int i, j;       // counter variables
long average;   // variable to store average
...

void loop(){
// input sensor data into oldest memory slot
sensVal[(i++) % 5] = analogRead(sensPin); 
average = 0;
for (j=0; j&lt;5; j++){
average += sensVal[j];   // add up the samples
}
average = average / 5;  // divide by total

</pre>
<p class='vspace'></p><p>The modulo operator can also be used to strip off the high bits of a variable. The example below is from the Firmata library.
</p>
<p class='vspace'></p><pre>    // send the analog input information (0 - 1023)
     Serial.print(value % 128, BYTE); // send lowest 7 bits  
     Serial.print(value &gt;&gt; 7, BYTE);  // send highest three bits  
</pre>
<p class='vspace'></p><h4>Tip</h4>
<p>the modulo operator will not work on floats
</p>
<p class='vspace'></p><h4>See also</h4>
<p class='vspace'></p><p><a class='wikilink' href='Arithmetic.html'>division</a>
</p>
<p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a>
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<p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?board=swbugs' rel='nofollow'>Forum</a>.</em>
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<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
<a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>.  Code samples in the reference are released into the public domain.
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